Survival After Ditching in Motorized Aircraft, 1989-2022.

INTRODUCTION: Although an unintended aircraft landing on water (referred to as ditching) is a rare event, the potential for occupant injury/fatality increases immediately following the event due to adverse conditions. However, to date, few studies have addressed the subject. Herein, ditching events and post-ditching survival were investigated.METHODS: Ditchings (1982-2022) in the United States were identified from the National Transportation Safety Board database. Occupant injury severity, aircraft type, pilot experience, flight conditions, and number of occupants were extracted. Poisson distribution, the Chi-squared test (2-tailed), Mann-Whitney U test, and Kruskal-Wallis one-way analysis of variance were employed.RESULTS: A total of 96 ditchings were identified. A systematic survey was hampered by the lack of a standardized reporting matrix in the reports. In total, 77 reports were included in the analysis. Across all ditchings, 128 of 169 (76%) occupants survived ditching and were rescued. Importantly, the initial ditching event was survived by 95% of all occupants. However, 32 (19%) occupants died post-ditching by drowning (21/32 cases) or for undetermined reasons. Considering probability per ditching event, in 26 (34%) of all ditchings, one or more occupants was/were fatally injured.DISCUSSION: Initial survival of the emergency ditching is high. Drowning was the leading cause of death after ditching and reduced the overall survival to 76%. Further investigation is needed to identify risk factors for fatal outcomes and/or improve probability of survival after ditching.Schick VC, Boyd DD, Hippler C, Hinkelbein J. Survival after ditching in motorized aircraft, 1989-2022. Aerosp Med Hum Perform. 2024; 95(5):254-258.

Deficient Aeronautical Decision-Making Contributions to Fatal General Aviation Accidents.

INTRODUCTION: General aviation (GA), mainly comprised of light (≤12,500 lb) aircraft, maintains an inferior safety record compared with air carriers. To improve safety, aeronautical decision-making (ADM) practices have been advocated to GA pilots since 1991. Herein, we determined the extent to which GA pilots disregard such practices.METHODS: Fatal accidents (1991-2019) involving private pilots (PPLs) in single-engine airplanes were identified (N = 1481) from the National Transportation Safety Board AccessR database. Of these, deficient go/no-go and in-flight ADM-related mishaps were scored using the PAVE (pilot, aircraft, environment, external pressure)/IMSAFE (illness, medicine, stress, alcohol, fatigue, eating) and PPP (perceive, process, perform) models, respectively. Statistical testing used Poisson distributions, Fisher exact tests, and Mann-Whitney U-tests.RESULTS: Of the 1481 accidents, 846 were identified as deficient ADM-related. Electing to depart into a hazardous environment (PAVE), disregarding wellness (IMSAFE), and poor aircraft familiarity (PAVE) represented the most common categories (54%, 21%, and 20%, respectively) of errant go/no-go ADM. A 64% decline in fatal accidents related to errant go/no-go decisions for the environment category was evident over the 30-yr period, with little decrements in the other domains. Within the errant environment-related category accidents, the decision to depart into forecasted adverse weather (e.g., degraded visibility, icing, thunderstorms) constituted the most prevalent subcategory (56%, N = 195). Surprisingly, of this subcategory, accidents were overrepresented by over nine- and threefold for instrument-rated PPLs disregarding icing and thunderstorm forecasts, respectively.CONCLUSION: With little decrement in ADM-related accidents in the pilot, aircraft, and external pressure domains, new strategies to address such deficiencies for PPLs are warranted.Boyd DD, Scharf MT. Deficient aeronautical decision-making contributions to fatal general aviation accidents. Aerosp Med Hum Perform. 2023; 94(11):807-814.

Use of flight tracking data to inform safety deficiencies for general aviation cross-country operations in challenging flying environments.

BACKGROUND: Air carriers, but not general aviation, have long employed in-flight data to identify risks/implement corrective measures for improved safety. Herein, using in-flight data, aircraft (in non-instrument-rated private pilots (PPLs) ownership) operations in two potentially hazardous environments (mountains, degraded visibility) were researched for safety practice deficiencies. Four questions were posed, the first two related to mountainous terrain operations: were aircraft (a) flown with hazardous ridge-level winds, (b) within gliding distance of level terrain? Regarding degraded visibility, did aviators (c) depart with low cloud ceilings (≤3,000 ft.), (d) fly at night away from urban lighting? METHODS: The study cohort comprised: (a) single engine aircraft in sole PPL proprietorship (b) registered in Automatic Dependent Surveillance-Broadcast (ADS-B-Out) equipage-required locations prone to low cloud ceilings in three mountainous states. ADS-B-Out data for cross-country flights (>200 nm) were collected. RESULTS: 250 flights (50 airplanes) were tracked (spring/summer 2021). For aircraft transiting areas subject to mountain winds influences, 65% completed one/multiple flights with potentially hazardous ridge-level winds. Two thirds of airplanes traversing mountainous topography would have, for at least one flight, been unable to glide to level terrain with a powerplant failure. Encouragingly, flight departures for 82% of the aircraft were with >3,000 ft. cloud ceilings. Likewise, flights for >86% of the study cohort were undertaken during daylight. Employing a risk scale, operations for 68% of the study cohort did not exceed low-risk (i.e., ≤1 unsafe practice) and high-risk flight(s) (three concurrent unsafe practices) were rare (4% of airplanes). In log-linear analysis, no interactions were evident between the four unsafe practices (p = 0.602). DISCUSSION: Hazardous winds and inadequate engine failure planning were identified as safety deficiencies for general aviation mountain operations. PRACTICAL APPLICATION: This study advocates for the expanded use of ADS-B-Out in-flight data to inform safety deficiencies/implement corrective measures toward improving general aviation safety.

Effect of lipid-lowering medications in patients with coronary artery bypass grafting surgery outcomes.

BACKGROUND: Increased life expectancy and improved medical technology allow increasing numbers of elderly patients to undergo cardiac surgery. Elderly patients may be at greater risk of postoperative morbidity and mortality. Complications can lead to worsened quality of life, shortened life expectancy and higher healthcare costs. Reducing perioperative complications, especially severe adverse events, is key to improving outcomes in patients undergoing cardiac surgery. The objective of this study is to determine whether perioperative lipid-lowering medication use is associated with a reduced risk of complications and mortality after coronary artery bypass grafting (CABG) with cardiopulmonary bypass (CPB). METHODS: After IRB approval, we reviewed charts of 9,518 patients who underwent cardiac surgery with CPB at three medical centers between July 2001 and June 2015. The relationship between perioperative lipid-lowering treatment and postoperative outcome was investigated. 3,988 patients who underwent CABG met inclusion criteria and were analyzed. Patients were divided into lipid-lowering or non-lipid-lowering treatment groups. RESULTS: A total of 3,988 patients were included in the final analysis. Compared to the patients without lipid-lowering medications, the patients with lipid-lowering medications had lower postoperative neurologic complications and overall mortality (P < 0.05). Propensity weighted risk-adjustment showed that lipid-lowering medication reduced in-hospital total complications (odds ratio (OR) = 0.856; 95% CI 0.781-0.938; P < 0.001); all neurologic complications (OR = 0.572; 95% CI 0.441-0.739; P < 0.001) including stroke (OR = 0.481; 95% CI 0.349-0.654; P < 0.001); in-hospital mortality (OR = 0.616; 95% CI 0.432-0.869; P = 0.006; P < 0.001); and overall mortality (OR = 0.723; 95% CI 0.634-0.824; P < 0.001). In addition, the results indicated postoperative lipid-lowering medication use was associated with improved long-term survival in this patient population. CONCLUSIONS: Perioperative lipid-lowering medication use was associated with significantly reduced postoperative adverse events and improved overall outcome in elderly patients undergoing CABG surgery with CPB.

General Aviation Flight Safety During the COVID-19 Pandemic.

BACKGROUND/OBJECTIVE: The COVID-19 virus has caused over 582,000 deaths in the United States to date. However, the pandemic has also afflicted the mental health of the population at large in the domains of anxiety and sleep disruption, potentially interfering with cognitive function. From an aviation perspective, safely operating an aircraft requires an airmans cognitive engagement for: 1) situational awareness, 2) spatial orientation, and 3) avionics programming. Since impaired cognitive function could interfere with such tasks, the current study was undertaken to determine if flight safety for a cohort of single engine, piston-powered light airplanes was adversely affected during a period of the pandemic (MarchOctober 2020) prior to U.S. approval of the first COVID-19 vaccine. METHODS: Airplane accidents were per the National Transportation Safety Board Access ^{database. Fleet times were derived using Automatic Dependent Surveillance-Broadcast. Statistics used Poisson distributions, Chi-squared/Fisher, and Mann-Whitney tests. RESULTS: Little difference in accident rate was evident between the pandemic period (MarchOctober 2020) and the preceding (JanuaryFebruary) months (19 and 22 mishaps/100,000 h, respectively). Similarly, a proportional comparison of accidents occurring in 2020 with those for the corresponding months in 2019 failed to show over-representation of mishaps during the pandemic. Although a trend to a higher injury severity (43% vs. 34% serious/fatal injuries) was evident for pandemic-period mishaps, the proportional difference was not statistically significant when referencing the corresponding months in 2019. CONCLUSION: Surprisingly, using accidents as an outcome, the study herein shows little evidence of diminished flight safety for light aircraft operations during the COVID-19 pandemic. Boyd DD. General aviation flight safety during the COVID-19 pandemic. Aerosp Med Hum Perform. 2021; 92(10):773779.}

Dosimetry of a novel converging X-ray source for kilovoltage radiotherapy.

PURPOSE: The objective of this work was to evaluate phantom dosimetry of a novel kilovoltage (kV) X-ray source, which employs a stationary tungsten anode and a linearly swept scanning electron beam. The source utilizes converging X-ray collimation along with orthogonal mechanical rotation to distribute surface flux over large area. In this study, this was investigated as a potential solution to fast-falloff limitations expected with kV radiotherapy. This was done with the aim of future clinical development of a lower cost radiotherapy alternative to megavoltage (MV) linac systems. METHODS: Radiochromic film was employed for dosimetry on the kV X-ray source of the linear-converging radiotherapy system (LCRS). The source utilizes charge particle optics to magnetically deflect and focus an electron beam along a stationary, reflection tungsten target in an ultra-high-vacuum stainless-steel chamber. Resulting X-rays were collimated into converging beamlets that span a large planar angle and converge at the system isocenter. In this study, radiochromic film dosimetry was done at 140 and 145 kVp for a designated planning treatment volume (PTV) of 4 cm diameter. An acrylic phantom was employed for dose distribution measurements of stationary and rotational delivery. Film dosimetry was evaluated in planes parallel to the source X-ray window at various depths, as well as in the plane of gantry rotation. RESULTS: At 140 and 145 kVp and using a collimated 4 cm square field at depth, lesion-to-skin dose ratio was shown to improve with additional beams from different relative source positions, where the different beams are focused at the same isocenter and do not overlap at the phantom surface. It was only possible to achieve a 1:1 Dmax -to-surface ratio with four delivery beams, but the ratio improved to 4:1 with 12 beams, focused at the same isocenter depth of 7.8 cm in an acrylic phantom. For the tests conducted, the following Dmax -to-surface ratios were obtained: 0.4:1 lesion-to-skin ratio for stationary delivery from one entry beam, 0.71:1 lesion-to-skin ratio was obtained for two beams, 1.07:1 ratio for four beams, and 4:1 for 12 beams. Dose-depth profiles were evaluated for stationary and rotational dosimetry. Additionally, rotational dosimetry was measured for a case more analogous to a clinical scenario, where the isocenter was located at an off-center simulated lesion. CONCLUSIONS: The results demonstrate potential dose-depth improvements with kV arc therapy by distributing the surface flux with a wide converging beam along with perpendicular mechanical source rotation of the LCRS. The system delivered tolerable dose to a large surface area when a threshold of multiple, separated beams was reached. The radiochromic film data support the feasibility of the construct of the LCRS kV radiotherapy system design.

Perioperative dexmedetomidine and 5-year survival in patients undergoing cardiac surgery.

BACKGROUND: Dexmedetomidine sedation has been associated with favourable outcomes after surgery. We aimed to assess whether perioperative dexmedetomidine use is associated with improved survival after cardiac surgery. METHODS: This retrospective cohort study included 2068 patients undergoing on-pump coronary artery bypass grafting and/or valve surgery. Among them, 1029 patients received dexmedetomidine, and 1039 patients did not. Intravenous dexmedetomidine infusion of 0.007 µg kg-1 min-1 was initiated before or immediately after cardiopulmonary bypass and lasted for < 24 h. The primary outcome was 5-year survival after cardiac surgery. The propensity scores matching (PSM), inverse probability of treatment weighting (IPTW), and overlap weighting approaches were used to minimise bias. Survival analyses were performed with Cox proportional-hazard models. RESULTS: The median age was 63 yr old and the male to female ratio was 71:29 in both groups. Baseline covariates were balanced between groups after adjustment using PSM, IPTW, or overlap weighting. Patients receiving dexmedetomidine in cardiac surgical procedures had higher survival during postoperative 5 yr in unadjusted analysis (hazard ratio [HR]=0.63; 95% confidence interval [CI], 0.51-0.78; P<0.001), and after adjustment with PSM (HR=0.63; 95% CI, 0.45-0.89; P=0.009), IPTW (HR=0.70; 95% CI, 0.51-0.95; P=0.023), or overlap weighting (HR=0.67; 95% CI, 0.51-0.89; P=0.006). The 5-yr mortality rate after cardiac surgery was 13% and 20% in the dexmedetomidine and non-dexmedetomidine groups, respectively (PSM adjusted odds ratio=0.61; 95% CI, 0.42-0.89; P=0.010). CONCLUSION: Perioperative dexmedetomidine infusion was associated with improved 5-yr survival in patients undergoing cardiac surgery.

Cardiac surgeons' concerns, perceptions, and responses during the COVID-19 pandemic.

BACKGROUND: The coronavirus disease 2019 (COVID-19) pandemic has had an unprecedented impact on health care and cardiac surgery. We report cardiac surgeons' concerns, perceptions, and responses during the COVID-19 pandemic. METHODS: A detailed survey was sent to recruit participating adult cardiac surgery centers in North America. Data regarding cardiac surgeons' perceptions and changes in practice were analyzed. RESULTS: Our study comprises 67 institutions with diverse geographic distribution across North America. Nurses were most likely to be redeployed (88%), followed by advanced care practitioners (69%), trainees (28%), and surgeons (25%). Examining surgeon concerns in regard to COVID-19, they were most worried with exposing their family to COVID-19 (81%), followed by contracting COVID-19 (68%), running out of personal protective equipment (PPE) (28%), and hospital resources (28%). In terms of PPE conservation strategies among users of N95 respirators, nearly half were recycling via decontamination with ultraviolet light (49%), followed by sterilization with heat (13%) and at home or with other modalities (13%). Reuse of N95 respirators for 1 day (22%), 1 week (21%) or 1 month (6%) was reported. There were differences in adoption of methods to conserve N95 respirators based on institutional pandemic phase and COVID-19 burden, with higher COVID-19 burden institutions more likely to resort to PPE conservation strategies. CONCLUSIONS: The present study demonstrates the impact of COVID-19 on North American cardiac surgeons. Our study should stimulate further discussions to identify optimal solutions to improve workforce preparedness for subsequent surges, as well as facilitate the navigation of future healthcare crises.

Analysis of Air Taxi Accidents (20042018) and Associated Human Factors by Aircraft Performance Class.

INTRODUCTION: Air taxis conduct nonscheduled transport and employ aircraft in various performance categories hereafter referred to as low, medium, and high performance, respectively. No study has yet addressed fixed-wing air taxi safety by performance category. Herein, we compared accident rates/occupant injury across air taxi airplane fleets grouped by performance category and identified human factors contributing to fatal accidents for airplanes in that category with the highest mishap rate.METHODS: Accidents (20042018) in the United States were identified from the National Transportation Safety Board database. General Aviation/Part 135 Activity Surveys provided annual fleet times. Fatal accident contributing factors were per the Human Factors Classification System (HFACS). Statistics utilized Poisson distributions, Chi-Square/Fisher, and Mann-Whitney tests.RESULTS: There were 269 air taxi mishaps (53 fatal) identified. Over the 15 yr, the accident rate (1.10/million flight hours-all categories) declined 50%, largely due to a reduction in medium/high performance category airplane crashes. However, little temporal change was observed for low performance airplanes (1.5/million flight hours) and injury severity trended higher. At the aircrew/physical environment levels, HFACS revealed decision (improper choices), skill-based (stick and rudder) and perceptual (night, instrument conditions) errors contributing to > 60% of fatal accidents involving low performance airplanes. At the organizational level, failing to correct problems, time pressures, and incentive systems contributed to 16% of fatal mishaps.CONCLUSION: Safety deficits remain for the low performance category air taxi fleet warranting increased pilot instrument flight training/utilization of the mandatory 3-axis autopilot in degraded visibility. Safety culture improvements to address issues of personnel/equipment/training deficiencies, failing to correct problems, and time pressures/a safety-compromising incentive system all need to be addressed.Budde D, Hinkelbein J, Boyd DD. Analysis of air taxi accidents (20042018) and associated human factors by aircraft performance class. Aerosp Med Hum Perform. 2021; 92(5):294302.

A comparison of general aviation accidents involving airline pilots and instrument-rated private pilots.

INTRODUCTION: The extremely low accident rate for U.S air carriers relative to that of general aviation (∼1 and ∼60/million flight hours respectively) partly reflects advanced airman certification, more demanding recurrency training and stringent operational regulations. However, whether such skillset/training/regulations translate into improved safety for airline pilots operating in the general aviation environment is unknown and the aim of this study. METHODS: Accidents (1998-2017) involving airline pilots and instrument-rated private pilots (PPL-IFR) operating non-revenue light aircraft were identified from the NTSB accident database. An online survey informed general aviation flight exposure for both pilot cohorts. Statistics used proportion testing and Mann-Whitney U tests. RESULTS: In degraded visibility, 0 and 40% (χ2p = 0.043) of fatal accidents involving airline and PPL-IFR airmen were due to in-flight loss-of-control, respectively. For landing accidents, airline pilots were under-represented for mishaps related to airspeed mismanagement (p = 0.036) relative to PPL-IFR but showed a dis-proportionate count (2X) of ground loss-of-directional control accidents (p = 0.009) the latter likely reflecting a preference for tail-wheel aircraft. The proportion of FAA rule violation-related mishaps by airline pilots was >2X (7 vs. 3%) that for PPL-IFR airmen. Moreover, airline pilots showed a disproportionate (χ2p = 0.021) count of flights below legal minimum altitudes. Not performing an official preflight weather briefing or intentionally operating in instrument conditions without an IFR flight plan represented 43% of airline pilot accidents involving FAA rule infractions. CONCLUSIONS: These findings inform safety deficiencies for: (a) airline pilots, landing/ground operations in tail-wheel aircraft and lack of 14CFR 91 familiarization regulations regarding minimum operating altitudes and (b) PPL-IFR airmen in-flight loss-of-control and poor landing speed management. Practical Applications: For PPL-IFR airmen, training/recurrency should focus on unusual attitude recovery and managing approach speeds. Airline pilots should seek additional instructional time regarding landing tail-wheel aircraft and become familiar with 14CFR 91 rules covering minimum altitudes.

Accident Rates, Causes, and Occupant Injury Involving High-Performance General Aviation Aircraft.

BACKGROUND: Spatial disorientation, poor situational awareness, and aerodynamic stalls are often causal/contributory to general aviation accidents. To mitigate against the occurrence of these mishaps Cirrus Aircraft has, since 2002, introduced advanced avionics into their piston airplanes (Cirrus SR20/22). These airplanes are also certificated to more rigorous crashworthiness tests than legacy aircraft approved prior to these standards being codified. Herein, using for comparison two legacy aircraft fleets manufactured prior to 2002, we determined whether a reduced mishap rate for all accidents or relating to the aforementioned causes/contributing factors and/or diminished injury severity for survivable accidents were evident for Cirrus SR20/22 airplanes.METHODS: Accidents (2008-2017) involving Cirrus SR20/22 airplanes (manufactured 2002 or later) and Beechcraft 35/36 (Bonanza) and Mooney 20 models (both manufactured no later than 2001) (14CFR Part 91 rules) were identified (N = 136, 259, 164, respectively) from the NTSB database. Statistical analyses used Poisson distribution/contingency tables/ t- and Mann-Whitney tests.RESULTS: For each year within the 2013-2017 timespan the Cirrus SR20/22 all-accident rate was diminished 39-75% relative to both legacy fleets. Temporally, the fraction of fatal Cirrus SR20/22 accidents, initially higher, declined 50% achieving a lower, or comparable, proportion to the two legacy airframes. Fatal accident rates involving spatial disorientation/situational awareness/aerodynamic stalls were > 80% lower for Cirrus SR20/22 airplanes. For survivable mishaps, Cirrus SR20/22 aircraft showed a lower proportion (0.13 compared with 0.20-0.35) of fatal/serious injuries.CONCLUSION: Toward improving legacy aircraft safety, owners should be encouraged to upgrade their avionics for mitigating against the occurrence of such human-factor-related mishaps and install airbags to minimize injury severity.Boyd DD, Howell C. Accident rates, causes, and occupant injury involving high-performance general aviation aircraft. Aerosp Med Hum Perform. 2020; 91(5):387-393.

Demarginalizing Stigmatized Identities of Transgender and Gender Nonconforming Individuals Through Affirmative Group Therapy.

Drawing from the existing literature on minority stress and stigma, this article highlights challenges - psychological, social, and interpersonal - confronting transgender and gender nonconforming (TGNC) individuals in relation to their gender identity and expression. TGNC individuals are at risk for poor health due to societal stigma and stressors they face as a gender minority group. Further, TGNC individuals may experience stigma in different shapes and forms; specifically, stigma may occur as enacted, felt, internalized, and anticipated stigma. In maintaining an identity that is socially devalued but often invisible to others, TGNC individuals confront additional challenges in negotiating the risks and benefits of disclosing their stigmatized identity. Affirmative group therapy is proposed as a strength-based and social justice-oriented approach for demarginalizing TGNC individuals' stigmatized identity. Group therapists are called on to address how forms of stigma impact TGNC individuals within and outside of the group, provide validation and space for practicing disclosure, highlight their strengths and resilience, and serve as social justice advocates.

Perioperative use of renin-angiotensin system inhibitors and outcomes in patients undergoing cardiac surgery.

It remains disputable about perioperative use of renin-angiotensin system inhibitors (RASi) and their outcome effects. This multicenter retrospective cohort study examines association between use of perioperative RASi and outcomes in patients undergoing coronary artery bypass graft and/or valve surgery. After the exclusion, the patients are divided into 2 groups with or without preoperative RASi (PreRASi, n = 8581), or 2 groups with or without postoperative RASi (PostRASi, n = 8130). With using of propensity scores matching to reduce treatment selection bias, the study shows that PreRASi is associated with a significant reduction in postoperative 30-day mortality compared with without one (3.41% vs. 5.02%); PostRASi is associated with reduced long-term mortality rate compared with without one (6.62% vs. 7.70% at 2-year; 17.09% vs. 19.95% at 6-year). The results suggest that perioperative use of RASi has a significant benefit for the postoperative and long-term survival among patients undergoing cardiac surgery.

Occupant Injury Severity in General Aviation Accidents Involving Excessive Landing Airspeed.

BACKGROUND: Of all phases of flight operations, accidents during landings are the most frequent. Of these, poor speed management during landing has ramifications for injury severity since: 1) impact forces increase as a square of forward velocity; and 2) an aerodynamic stall, associated with inadequate landing speed, imparts high vertical G forces. Herein, the proportion of landing accidents involving deficient airspeed control and occupant injury severity was determined.METHODS: General aviation landing accidents (1997-2016) were identified from the NTSB database. An accident involving high-airspeed (high-energy) was one for which the NTSB cited airplane porpoising, multiple bounces, or floating, whereas an inadequate airspeed related (low energy) mishap was one citing this term or in which an aerodynamic stall occurred. An anonymous online survey of certificated pilots was used to inform landing technique. Statistical analyses used Poisson distribution and Chi-squared tests.RESULTS: Relative to the earliest period (1997-2001), the landing accident rate was undiminished for more recent years (2007-2016). Of 235 accidents, 38% involved high-energy, whereas 4% were inadequate airspeed-related. For the former, 17% resulted in occupants with fatal-serious injuries, twofold higher than for mishaps with no evidence of mis-speed. Of 1392 survey respondents, 73% selected a landing airspeed higher than required for an under-maximum weight airplane.CONCLUSION: For landing accidents involving airspeed mismanagement, those related to excessive energy predominate and are associated with more severe injuries. Two mitigating strategies are advanced: 1) pilot training should discuss landing airspeed adjustment for aircraft weight; and 2) installation of inflatable restraints for reducing injury severity should be encouraged.Boyd DD. Occupant injury severity in general aviation accidents involving excessive landing airspeed. Aerosp Med Hum Perform. 2019; 90(4):355-361.

Monte Carlo calculated kilovoltage x-ray arc therapy plans for three lung cancer patients.

Purpose: The intent of this work was to evaluate the ability of our 200 kV kilovoltage arc therapy (KVAT) system to treat realistic lung tumors without exceeding dose constraints to organs-at-risk (OAR).Methods and Materials: Monte Carlo (MC) methods and the McO optimization framework generated and inversely optimized KVAT treatment plans for 3 SABR lung cancer patients. The KVAT system was designed to treat deep-seated lesions with kilovoltage photons. KVAT delivers dose to roughly spherical PTVs and therefore non-spherical PTVs were divided into spherical sub-volumes. A prescription dose of 12 Gy/fx × 4 fractions was planned to 90% of the PTV volume. KVAT plans were compared to VMC++ calculated, 6 MV stereotactic ablative radiotherapy (SABR) treatment plans. Dose distributions, dose volume histograms, gradient index (GI), planned mean doses and plan treatment times were calculated. Dose constraints for organs-at-risk (OAR) were taken from RTOG 101.Results: All plans, with the exception of the rib dose calculated in one of the KVAT plans for a peripheral lesion, were within dose-constraints. In general, KVAT plans had higher planned doses to OARs. KVAT GI values were 5.7, 7.2 and 8.9 and SABR values were 4.6, 4.1, and 4.7 for patient 1, 2 and 3, respectively. KVAT plan treatment times were 49, 65 and 17 min for patients 1, 2 and 3, respectively.Conclusions: Inverse optimization and MC methods demonstrated the ability of KVAT to produce treatment plans without exceeding TG 101 dose constraints to OARs for 2 out of 3 investigated lung cancer patients.

Perioperative aspirin and long-term survival in patients undergoing coronary artery bypass graft.

This study aimed to examine association between perioperative uses of aspirin and long-term survival in patients undergoing CABG. A retrospective cohort study was performed in 9,584 consecutive patients receiving cardiac surgery from three tertiary hospitals. Of all the patients, 4,132 patients undergoing CABG met inclusion criteria and were divided into four groups: with or without preoperative or postoperative aspirin respectively. 30-day postoperative and long-term mortality were compared with the use of propensity scores and inverse probability weighting adjustment to reduce the treatment-selection bias. The patients taking preoperative aspirin presented significantly more with comorbidities. However, the results of this study showed that preoperative aspirin (vs. no preoperative aspirin) was associated with significantly reduced the risk of 30-day mortality in the patients undergoing CABG. Further, the results of long-term mortality showed that the patients taking preoperative aspirin and postoperative aspirin (vs. not taking) were associated with significantly reduced the risk of 4-year mortality (14.8% vs. 18.1%, RR: 0.82, 95% CI: 0.75-0.89, P = 0.005; 10.7% vs. 16.2%, RR: 0.66, 95% CI: 0.50-0.82, P = 0.003). In conclusion, this cohort study showed that perioperative (before and after surgery) use of aspirin was associated with significant reduction in 30-day mortality without significant bleeding complications, also improved long-term survival in patients undergoing CABG.

A comparison of special category light-sport and corresponding type-certificated aircraft safety.

INTRODUCTION: The special category light sport airplane (light sport) sector of general aviation has grown 10-fold in as many years with solo operations requiring only a sports pilot's certificate. With little research on light sport airplane safety, the study objective was to compare light sport and type-certificated airplane accident rates. METHOD: Accidents were identified from the National Transportation Safety Board database. Statistics employed Poisson distribution/proportion analyses/Mann-Whitney U-tests. RESULTS: For the 2009-2015 period, the light sport airplane accident rate (fatal/non-fatal combined) was >15-fold higher than comparable type-certificated aircraft, undiminished over time. The excessive light sport airplane accident rate was associated with inferior airman experience (time-in-type, certification). Mishaps were most frequent during landing (40%) and, of these, nearly half were due to a deficiency in the flare. There were a dis-proportionate number of trainees involved in landing accidents compared with mishaps for other phases of operations. CONCLUSION: Towards improving safety, additional light sport training with emphasis on landings and a focus on the flare and directional control is warranted. PRACTICAL APPLICATION: In the confines of the present study considering that landing mishaps, the most common accident cause, are often related to deficiencies in the flare and loss-of-directional control, instructors should ensure that airmen have mastered these aspects of landing and, for trainees, acquired the appropriate visual monocular cues.

General Aviation Accidents Involving Octogenarian Airmen: Implications for Medical Evaluation.

BACKGROUND: No upper age limit exists at which general aviation pilots are disallowed from exercising their flying privileges. Operating an aircraft, and landing in particular, requires high visual acuity, cognitive function, and eye-hand/foot coordination; i.e., functions which commonly deteriorate with age. No studies have addressed flight safety of airmen ≥ 80 yr of age (octogenarian+ or 80+) or whether such airmen are more landing accident-prone. This research seeks to answer these questions. METHODS: Accidents and private pilot-certificated airmen counts were obtained from the National Transport Safety Board accident database and the U.S. Civil Airmen Statistics, respectively. Contingency tables were used to determine differences in proportions. A Poisson distribution was employed to determine whether airmen count (80+ and 30-39 yr) and their accident rates differed over time. Differences in median values were tested with a Mann-Whitney test. RESULTS: The proportion of airmen 80+ years doubled and their accident rate increased (6 and 11 mishaps/1000 airmen, respectively) between 2002 and 2016. Landing accidents were over-represented for octogenarian+ pilots compared with airmen 30-39 yr (31 and 17%, respectively) and did not reflect inferior experience but were often due to an aircraft flaring deficiency. The proportion of fatal accidents was comparable (11 and 13%, respectively) for the older and younger age cohorts. CONCLUSION: A growing population and a climbing accident rate for octogenarian+ airmen were evident. The disproportionate count of pilots involved in landing mishaps raises a concern for an increase in such mishaps for octogenarian airmen opting for BasicMed due to less restrictive/frequent visual acuity tests.Boyd DD. General aviation accidents involving octogenarian airmen: implications for medical evaluation. Aerosp Med Hum Perform. 2018; 89(8):687-692.

Robotic-assisted coronary artery bypass surgery: an 18-year single-centre experience.

BACKGROUND: Minimally invasive robot-assisted direct coronary artery bypass (RADCAB) has emerged as a feasible minimally invasive surgical technique for revascularization that might offer several potential advantages over conventional approaches. We present our 18-year experience in RADCAB. METHODS: Between February 1998 and February 2016, 605 patients underwent RADCAB. Patients underwent post-procedural selective graft patency assessment using cardiac catheterization. RESULTS: The mortality rate was 0.3%. The rate of conversion to sternotomy for any cause was reduced from 16.0% of the first 200 cases to 6.9% of the last 405 patients. The patency rate of the LITA-to-LAD anastomosis was 97.4%. Surgical re-exploration for bleeding occurred in 1.8% of patients, and the transfusion rate was 9.2%. Average ICU stay was 1.2 ± 1.4 days, and average hospital stay was 4.8 ± 2.9 days. CONCLUSIONS: Robot-assisted coronary artery bypass grafting is safe, feasible and it seems to represent an effective alternative to traditional coronary artery bypass grafting in selected patients.

In-Flight Decision-Making by General Aviation Pilots Operating in Areas of Extreme Thunderstorms.

BACKGROUND: General aviation (comprised mainly of noncommercial, light aircraft) accounts for 94% of civil aviation fatalities in the United States. Although thunderstorms are hazardous to light aircraft, little research has been undertaken on in-flight pilot decision-making regarding their avoidance. The study objectives were: 1) to determine if the thunderstorm accident rate has declined over the last two decades; and 2) assess in-flight (enroute/landing) airman decision-making regarding adherence to FAA separation minima from thunderstorms. METHODS: Thunderstorm-related accidents were identified from the NTSB database. To determine en route/arriving aircraft real-time thunderstorm proximity/relative position and airplane location, using a flight-tracking (Flight Aware®) website, were overlaid on a graphical weather image. Statistics employed Poisson and Chi-squared analyses. RESULTS: The thunderstorm-related accident rate was undiminished over the 1996-2014 period. In a prospective analysis the majority (enroute 77%, landing 93%) of flights violated the FAA-recommended separation distance from extreme convection. Of these, 79 and 69% (en route and landing, respectively) selected a route downwind of the thunderstorm rather than a less hazardous upwind flight path. Using a mathematical product of binary (separation distance, relative aircraft-thunderstorm position) and nominal (thunderstorm-free egress area) parameters, airmen were more likely to operate in the thunderstorm hazard zone for landings than en route operations. DISCUSSION: The thunderstorm-related accident rate, carrying a 70% fatality rate, remains unabated, largely reflecting nonadherence to the FAA-recommended separation minima and selection of a more hazardous route (downwind) for circumnavigation of extreme convective weather. These findings argue for additional emphasis in ab initio pilot training/recurrency on thunderstorm hazards and safe practices (separation distance and flight path).Boyd DD. In-flight decision-making by general aviation pilots operating in areas of extreme thunderstorms. Aerosp Med Hum Perform. 2017; 88(12):1066-1072.